The present invention relates to a novel rifamycin derivative or salts thereof, a process for preparing the same and antibacterial agents containing the same as an effective component. More particularly, the present invention relates to a novel rifamycin derivative having the general formula (I): ##STR2## wherein R.sup.1 is hydrogen atom or acetyl group; R.sup.2 is hydrogen atom or hydroxyl group; A is a group represented by the formula: ##STR3## wherein R.sup.3 is an alkyl group with 1 to 5 carbon atoms or an alkoxyalkyl group with 2 to 6 carbon atoms and R.sup.4 is an alkyl group with 1 to 5 carbon atoms, a group represented by the formula: --CH.sup.2).sub.a X.sup.1, wherein a is 1 to 4 and X.sup.1 is ethynyl group, cyano group, a group having the formula: ##STR4## wherein R.sup.5 and R.sup.6 are the same or different from each other and are hydrogen atom or an alkyl group with 1 to 3 carbon atoms, a group represented by the formula: OR.sup.7, wherein R.sup.7 is hydrogen atom or an alkyl group with 1 to 4 carbon atoms, a group represented by the formula: ##STR5## wherein R.sup.8, R.sup.9 and R.sup.10 are the same or different from each other and are hydrogen atom or an alkoxy group with 1 to 3 carbon atoms, or a group represented by the formula; ##STR6## wherein R.sup.11 and R.sup.12 are the same or different from each other and are an alkyl group with 1 to 3 carbon atoms; a cycloalkyl group with 3 to 8 carbon atoms, a group represented by the formula: ##STR7## wherein R.sup.13 is hydrogen atom or an alkyl group with 1 to 3 carbon atoms, or a group represented by the formula: --CH.sub.2 (CHOH).sub.4 CH.sub.2 OH; a group represented by the formula: ##STR8## wherein ##STR9## is a 3 to 10 memebered cyclic amino group with 2 to 9 carbon atoms, X.sup.2 is hydrogen atom or an alkyl group having 1 to 4 carbon atoms and X.sup.3 is hydrogen atom, an alkyl group with 1 to 3 carbon atoms, hydroxyl group, a group represented by the formula: ##STR10## wherein R.sup.14 and R.sup.15 are the same or different from each other and are hydrogen atom or an alkyl group with 1 to 4 carbon atoms, a hydroxyalkyl group with 1 to 3 carbon atoms or cyclic or noncyclic amino group with 2 to 6 carbon atoms, or X.sup.2 and X.sup.3 when taken together represent=0 group or the group represented by the formula: --O (CH.sub.2).sub.b O--, wherein b is 2 to 4, a group represented by the formula: ##STR11## wherein c and d are the same or different from each other and are 1 to 4, a group represented by the formula: ##STR12## wherein e and f are the same or different from each other and are 1 to 4, or a group represented by the formula: ##STR13## wherein g and h are the same or different from each other and are 1 to 4, R.sup.16 and R.sup.7 are the same or different from each other and are hydrogen atom or an alkyl group with 1 to 3 carbon atoms and X.sup.4 is oxygen atom, sulfur atom or a group represented by the formula: NR.sup.18, wherein R.sup.18 is hydrogen atom, an alkyl group with 1 to 3 carbon atoms, a phenyl group represented by the formula: ##STR14## wherein R.sup.19 is hydrogen atom or trifluoromethyl group, or a group represented by the formula: ##STR15## wherein R.sup.20 and R.sup.21 are hydrogen atoms or when taken together represent the group having the formula: --OCH20--, or salts thereof, a process for preparing the same and antibacterial agents containing the same as an effective component.
The rifamycin derivative of the present invention is a novel compound which has not yet been reported in the literature.